Radio receiving system



sept. 11, 1928. 1,684,361

W. T. POWELL RADIO RECEIVING SYSTEM T11- lll E Tf $1 LNH-11|4 NIH l l m INVENTOR .l NW3' 5141- Wfww sm. 11, 192s.

1,684,361 W. T. POWELL RADIO RECEIVING SYSTEM Filed Nov. 14, 1925 5 Sheets-Sheet 2 INVENTOR Sept. 1l, 1928. 1,684,361

w. T. POWELL RADIO RECEIVING SYSTEM Filed Nov. 14, 1925 3 Sheets-Sheet 3 l f I L-j l s N l 1' l @EL n Lo l o' g H o' n' LI- V/ L1- I- (im-Wj \o l l ein Patented Sept. 11, 1928.

UNITED STATES eATEirrv oFFicE..

WINFRED T. POWELL, OF ROCHESTER, NEW YORK, ASSIGNOR TO THE STROMBERG- CARLSON TELEPHONE IiANUFACTRN-G COMPANY, 0F ROCHESTER, NEW YORK, .A

CORPORATION OF NEW YORK.

RADIO RECEIVING SYSTEM.

Application filed November This invention relates to radio receiving systems and more particularly to such radio receiving systems as are used for broadcast reception.

More. specifically this invention relates to the use of telephone lines in either manual or automatic telephone systems for receiving radio broadcast programs.

One of the features of this invention resides in providing lneans by which the circuits ot a radio receiver are simplified.

Another feature is the provision of means by which the timing adjustments of a radio receiver are eliminated.

Another feature of this invention is the provision of means by which the timing of a radio receiving circuit is accomplished at a distant point such as a telephone exchange.

A. further feature of this invention is the provision of means by which radio programs are received over the usual telephone lines,

Still another feature of this invention is the provision of means by which a regular telephone line may be used for usual telephone service aty the saine time that it is being used to receive a radio program. i

An additional feature of this invention is the provision of means whereby different radio stations may be selected by connecting to different. numbers in a telephone system.

A further feature of this invention is the provisionl of means such that` when a radio program is being received over a telephone line, the disconnection from the radio receiving circuit may be controlled either by the subscriber or by the central oliice operator.

Other features of this invention will be apparent from the following description when read in connection with the accompaiiying drawings.

The novel featuies which are considered characteristic of this invention are particulaily set forth in the appended claims.

It is well understood that in order for radio broad asting to be most etfcctive, the upper power level must bey main aiiied high possible over large arcas. By the use of .so-called siipeip .iwer broadcasting stations, there is an excessively high power level in the neighborhood of the broadcasting station and this level falls otl rapidly with increase in distance from the station.

Systems are Well known in which pro- 14, 1925. Serial No. 69,132.

grams of music, news, information and the like are distributed over wire lines, received at local broadcasting stations and then broadcast by wireless from these local stations. In these systems there is not an eX- cessive amount of power atv any point, the power level being more uniform. The radio signals in a system of this type, after being translated into wireless signals are subject to interference, such as' static, signals from other stations. etc.

In the system of this invention, it is proposed to first receive radio programs at :i central station such as a telephone exchange` after which these programs are distributed to telephone subscribers by Way of the usual line circuits. These programs may be received at the central telephone exchange, either over wir(` lines from the distant broadcasting studio or by means of carrier waves through the ether.

In this system there is no need for using an excessive amount of power for sending out the radio signals, since they are sent over wire circuits in which the signals are directed to their required destination with sniall loss. Neither will the signals in this system be subject to such interference as previously was the case, because they are translated into relatively low frequency waves before being connected to the tele/- phone lines and these low frequency waves are not so sensitive to static and other influences, are the extremely high frequency waves.

Although shown applied to an automatic telephone system, it will be readily understood that the system of this invention may equally well be operated in a manual telephone system. It is thought that the invention will best be understood by first describing the operation of the circuits in connection with a regular automatic telephone conVA nection. after which a connection to the central oitice radio receiving circuit will be described.

rl`he drawings with Fig. 3 arranged to the right of Figs. l and Q show one forni of the invention.

Fig. l shows. in schematic form, the layout of the system of this invention.

Fig. 2 shows the telephone substation circuit together with the radio receiving cirfill cuit located at the subscribers station, also the rotary line switch circuits.

ln Fig. 3 is shown a connector circuit which is used for regular telephone connections1 also a special third selector circuit with its associated control switch used for connecting to the central oflice radio receiving circuit. ln this ligure certain radio circuits are indicated. such as an amplifier, an oscillator and a receiver, the function of which will be pointed out in the detailed de script ion, which follows.

Fig. 1- illustrates a circuit which may be substituted for the radio receiver circuit shown in the lower left hand portion of Fig. f2 and Fig. 5 shows a circuit of the central otiice radio receiver, which may be substituted for the central otlice radio receiver shown at the right, central portion of Fig. 3. lloth of these substitutions constitute an alternative forni of the invention in which a sfo-called short wave receiver is used at the central otiice, the operation of which will be described.

Fig. (l shows a circuit of the central ottice radio receiver. which may be substituted for the central office radio receiver shown at the iight, central portion of Fig. Both of these substitutions constitute a further modification of the invention by which radio programs are received over wire lines from a distant. broadcast station and these programs selected by telephone subscribers` as will be described.

Referring to Fig. 1 of the drawings, Tl,

and T represent three telephone substations connected over the usual line circuits to associated primary line switches Ll, L2 and Lit.

FF and S" represent three tirst selectors and S1, S5 and S represent three second lselectors, all ot which are comnmnly used in automatic tclejiihone systems. ("1 and C2 represent the usual connector type switches as used in automatic telephone systems. while lll and lli refer to special third se legtors.

J, ,l2 and J indicate three manual tele.- phone jacks aljipearing before one or more special attendants or operators. while P1, l2 and P refer to plugl and cord circuits associated with radio receivers A1. A2 and A3. lie-low the line switches L1, L2 and L3 are shown two special line switches LV1 and L5, whose bank contacts are multipled with those of the regular line switches L1, L2 and L3.

lVith further reference to Fig. 1, the operation of this system in general is as followsz-tertain numbers in the automatic telephone exchange are assigned for use in icceiving radio programs and when these numbers arc dialled, subscribers may listen to the particular program being received.

It will be assumed that the subscriber represented at T1 desires to obtain a telephone connection with the subscriber represei'ited by T2. lVhen the first mentioned subscriber removes the receiver from its switchhook, line switch L1 functions to select an idle trunk such as B1 leading to first selector Sl. The firstv digit of the wanted number will now be dialled, this being effcctive to cause lirst selector S1 to advance to the level corresponding to this first digit, after which it will select an idle trunk in this level such as B2 associated with a second selector St. The second digit is now dialled and this etfective to cause the second selector St to advance to the level corre spending to the second digit, after which it will automatically select an idle trunk such as B3 associated with a connector switch (l1.

Assuming this to be a four digit system, the third and fourth digits dialled will be effective to cause connector Cl to make connection with the number in its bank associated with a connection such as B4 leading back to the line circuit of substation T2. It will be understood that in the case of systenis having more than four digits, it is only necessary to introduce other selector groups between the selectors indicated by S4, S and S and the connectors indicated by Cl and C2.

lt will now be assumed that the subscriber associated with telephone substation T1 desires to receive a radio program from KDKA, and that programs being received from this station are selected by subscribers dialling number 2811. The calling subscriber at T1 removes the telephone receiver from its switchhook which is etlective to cause line switch L1 to select an idle trunk such as l associated with second selector til, The tirst digit of the special number is now dialled, which is ellcctive to advance the tirst selector S1 to the second level, :fter which this selector' will connecttoatrunk such as l: leading to an idle second selector tit. The second digit is now dialled, which is ell'cctive to advance the second selector to the eighth level, after which this second selector will connect to a trunk such as Il leading to special third selector R1. The third and fourths digits (11) are now diallcd` causing selector R1 to connect to a trunk such as l5 leading to jack J1. The selection of this special number is effective to light a lamp associated with this number before the special radio operator. This lamp is an indication to this operator that she is required to connect a radio receiving set such as A, which is receiving a program from KDKA to the calling line. She does this by inserting plug P1 into jack J1.

lt should be noted at this time that a special second selector level is used to connect to special third selectors Rl and R2 for connecting to radio receiving circuits. Other second selectors levels lead to connector switches and are used t'or regular telephone service.

The calling subscriber now dials his own number. which operation is etlective to extend the. central otllce radio receiver circuit A1 to the calling line. As soon as the last digit ont the special ninnber is dialled, a circuit condition is set up which causes a line switch such as L4, associated with the special third selector used, to automatically select an idle lirst selector such as The selection ot his own number, by the calling` subscriber, is etlective to cause lirst selector S2, a second selector' such as and a connector such as C1 to connect with the calling line. lVhen this latter connection is made, the usual busy test circuit ot the connector is disabled in order that the connection may be made to the calling line. The telephone receiver is now placed on the switchhook and the radio program is received, over a simplex circuit including the calling line, until this spcial connection is released. This release may be brought about by the operator, if the subscriber neglects to release the connection, at'ter the broadcast station terminates the program. The subscriber may release the c'onirietion by dialling a special release number which is elfective to restore the operated switches to normal. Another number associated with a dilferent broadcast station. for ef;- ample 2812 associated with lVGY, may now be dialled, the operation of which is similar to that above described.

Detailed operar/'0a.

Assuming that the subscriber, whose substation is represented by '1" desires to estalish a connection with the subscriber. whose substation is represented by T2, the removal of the receiver from the` switchhook at substation "l will close a circuit over the calling line and calling substation in .series through the lel't hand windings ot' repeating coil l and both windings otl impulse relay 2 to battery and ground. This circuit is oliective to operate relay 2. which in turn closes a circuit by way ot its make contact and the right hand windings cf repeating coil 1 to ground aty the upper back contact ot' cut-ofi relay 3 and to grounded battery through the windingr ot line relay l. This circuit closure causes the indiyidual line switch l. associate-:l with the calling line to test for and seize an idle outgoing trunk leading to a lirst selector.

Assuming that the trunk is busy upon which the wipers of switch L1 are connected, there will be a ground on terminal 5 associated with this trunk, which ground is effective to cause the operation of stepping magnet 6 over a circuit which may be traccil Contact of from battery, winding and back contact of stepping magnet 6, upper make line relay 4, inner, upper back contact of cutaillA relay 3 and wiper 7 to ground on contact` At this time there will be a ground connected by way ot the lower make contact of relay fl to one side ot' cutotl' relay 3 and the previously mentioned ground from test terminal 5 will be applied to the other sine ol cut-ollI relay 3, thus short circuiting and preventing the operation ol' relay 3 when test brush i' encounters busy trunks.

Assuming that the tirst idle trunk tested is that one to which trunk cor-.ductors 8, S), l() and 1l are associated. there will be no ground on conductor 8 in this instance. circuit is now ell'ective to operate relay 3, traceable from grounded battery, winding and back contact oli magnet (5, winding of relay l and lower make contact of relay l to ground. Relay t3 operates and extends the closed circuit, consisting ot' the right hand windings` of repeating coil l, by way of wipers 12 and lll and trunk conductorsl 9 and lt) to the line relay ot the chosen 'irst selector.

The operation of the calling subscribers dia Yt'or recording the tirst and second digits of the 'anled number etlective to advance the lirst and second selectors to the proper trtmks lor connecting to an idle connector switch, such as C1 ot Fig. 3. The dotted portions ot" conductors S, l), lt) and ll, which trad to connector switch indicate that tirst and second selectorsl are interposed be tween the line switch and connector, if this system is a tour digit system. lt is well understood that in case ol systems o't the larger type, there will be other selectors such as third selectors and fourth selectors in addition to tirsts and seconds.

ln order to simplify the drawings and the description ot' this invention. it is not believed necessary to show complete circuits ol' these tirst and second selectors. since they may be like those .shown at ll of the patent to ll'. T. Powell. Ro. 1,350,852, patented August 2l, mit). ln this patent it is shown how line coinluctors such as 9 and lt). a rcleasc trunk conductor such as 8 and an extra conductor such as ll may he carriel through the tirst, second and other selectors to the tinal or connector .switch circuit. ln the above mentioned patent these conductors are connected through the selector switch ll by means olE wipers 2l, 22. 23 and 2l.

The closed circuit through the right hand windings of repeating coil l by way ol' conductors t) and lt) is now ell'ective to operate impulse relay ll ol the connector switch and this relay at its front contact closes a circuit for operating` the slow releasing relay 15. Relay l5 at its left hand jfrontr contact closes a circuit from ground. conductor 8, wiper T, inner, upper make contact of relit) lay 3, winding of relay 3, back contact and winding ot magnet G to grounded battery. This circuit functions to maintain relay 3 in its operated position and also to make this particular connector switch test busy to other calling lines.

The calling subscriber now operates the dial in accordance with the tens digit ot the wanted number, which causes relay 2 to retract and attract its armature in synchronisni with the dial impulses. Relay 2 acts as a repeating relay by opening and closing the circuit ot' the right hand windings ot repeating coil 1, which in turn causes relay 14 to retract and attract its armature a number ot' times corresponding to the tens digit ot the wanted line. At each retraction of the armature ot relay let, a circuit is closed trom ground, back contact ot this relay, make contact ot' relay 15, winding ot' changeover relay 16, winding` ot' primary magnet 17 and side switch wiper 18 in its tirst position to grounded `battery. This circuit is ettective to cause the advance ot the connector switch to the group ot' lines represented by the tens digit. This circuit is also ell'ective to cause the operation ot change-over relay lt, which in turn closes a circuit from ground, make contact ot relay 1G and winding oi escape magnet 21 to grounded battery. At the termination ot the series ot impulses corresponding to the tens digit, relay 1l maintains its armature attracted tor a relatively long interval which allows relay 16 to release, this latter relay opens the circuit ot escape magnet 21 allowing this magnet to release and advance the side switch wipers troni their tirst to their second position.

The calling subscriber now operates the dial in accordance with the units digit ot' the wanted number, this operation being ctl'ectivc to again cause the retraction and attraction ot' relay lt a number ot times corm responding to the units digit. At each retraction o't' the armature ot' relay 14, a circuit is closed trom ground, back contact ot relay 1i. make contact ot relay l5, winding ot relay lt. back contact ot busy relay 19, winding ot secondary stepping magnet 2() and the second position ot side switch wiper l'to grounded battery.

This circuit is etl'ective to advance the connector switch in its secondary movement to select and test the terminals associated with the wanted line. At the time the arl'nature ot relay 1-1 is retracted, the circuit ot relay 1.7 is open. but since this relay is slow to reir; it will maintain its armature attracted until relay 1l energizes and again closes the circuit ot relay 15.

During the operation ot relay 11, the circuit` from ground at its back contact. which etective to advance the secondary magnet 20. is also etlective to cause the operation ot relay 1G. This relay being slow to release maintains its armature attracted during the sending ot' the units series of '11npulses and at its make contact closes a circuit tor operating and holding escape magnet 21 until the end ot this series of impulses, when relay 16 releases and opens the circuit of magnet 21 tor releasing this magnet and advancing the side switch wipers trom their second to their third position. The above is assuming that the wanted line is idle.

A circuit is now closed trom ground, side switch wiper 22 in its third position, back contact of relay 223, connector wiper 24, terminal 25 associated with the called line. and winding 26 representing the called line cut ott relay, to grounded battery. This circuit is eliqectire to make the called line lousy and also to operate the cut-ott relay 26 of the called line switch. Another circuit is closed from ground, side switch wiper in its third position, back contact ot relay 23, winding of relay 2S) and side switch wiper 18 in its third position to grounded battery. This circuit is effective to operate the cutthrougl relay 29 for connecting lto the line circuit ot' the called line. The circuit for ringing the bell ot the called substation may now be traced 'from the common generator (not shown), wire 27, upper back contact ot trip relay 2S, upper make contact ot relay 29 connector wiper 30, terminal 31, upper side ot the called line, called substation bell, lower side ot the called line, terminal 32, connector wiper 2li', inner make contact of relay 20, inner, upper back Contact and upper 'inding et relay 28 to grounded battery. Relay 28 so designed that it will not operate when alternating ringing current tor ringing the called bell flowing through its upper vinding, as above described, but when the called subscriber removes the receiver 'troni the switchhook, a direct current circuit is closed over the above traced circuit tor energizing relay This relay closes its lower make contact before opening either ot its back contacts, which .stablishes a locking circuit t'or itselt from grounded battery, lower winding and lower make contact ot relay 28, to ground at ott-normal contact 34. Talking battery is applied to the called line through windings ot' impedance coil 35 and upper make contacts ot' relay 2S, while talking battery to the calling line is applied through windings ot' relay 2.

t the close oi conversation, the release of the connection is controlled by the calling subscriber, who. upon replacing the receiver on its switchhook, opens the calling line and causes relay 2 to retract its armature. This opens the circuit through the right hand windings ot repeating coil 1 and the wind# ings ot relay 14 ot the connector switch, which is etllective to release this latter relay and in turn open the circuit et, and release the relay 15. Relay 15 at its lett hand make Contact removes the ground from conductor 8, thereby releasing relay 3 of the calling line switch, thus restoring` the circuit of this line switch 'to its normal condition. The release ot' relay 15 closes circuit from ground, left hand back contact, oft-normal contact 3G and winding of release magnet 37 to grounded battery. This circuit is effective to operate the release magnet which in turn restores the connector switch to its normal position.

Assuming the called line to be busy at the end of the units series of impulses, a circuit to ground will be found on terminal 25 associated with this line. At the close of the units series of impulses, relay 16 retracts its armature and closes a circuit from grounded battery, winding of' escape magnet 21, continuity spring` and back contact of relay 16, winding of busy relay 19, continuity spring and back Contact of relay 19, side s 'itch wiper 22 in its second position, back contact of relay 23, wiper 2l and terminal 25 to ground. It will be understood that this groundwhich makes the called line busy. may either be applied to terminal b v means of' a side switch wiper 22 in its third position ot' some other connector switch, similar to C or it may be applied to terminal from the ground on a trunk similar to 8 to which the called line switch is connected, if this line is busy due to an originating call.

The above traced circuit to ground through relay 19 is effective to ope ate this relay and to hold escape magnet 21 operated, thus maintaining the side switch wipers in their second position. The operation of relay 19 connects a source of busy tone current, BZ, to the calling line as an indication of the busy condition of the called line. Relay 19 and magnet 2l are now locked operated to ground at oft-normal contact 3l until the release of the connection.

lt will be noted that line switches, similar to L associated with calling lines are equipped with three wipers such 7, 12 and 1? and that the trunks to which these line switches connect are three-wire trunks. Conductor 1l is not multiply connected to the bank contacts of line switches, such as L1, L2 and L3, but it is only wired to the bank contacts of' special line switches, such as L4 and L5. The line and release trunks 9, 1() and 8 are multiply connected to these special line switches, as well as to regular line switches.

lt will now be explained how a calling subscriber may connect a calling telephone circuit, such as T1, with a radio receirer circuit, such as A1.

Assume that the callingsubscriber whose substation is represented by T1 desires to receive a program from KDKA and that #-2811 is assigned tor receiving programs Jfrom this particular' radio broadcast station. The calling subscril er upon removing the receiver from its switchhook causes line switch L1 to connect with a first selector as previously described in connection with a regular automatic telephone connection. The first and second digits (28) are now dialled, causing first and second selectors to be opi-rated in the manner previously described, except in this case the second selector will advance to a group of trunks leading to special third selectors, such as Rl. It will be understood that the' trunk lines 43, 44 and l5 are connected to a numberl of multiply connected bank contacts associated with the group orn second selectors.

Assuming that the second selector selects a trunk represented by trunk conductors 43, ll and 15, the closed circuit at the make contact of relay 2 by way of line switch wipers 12 and 13 will be extended by way of' conductors 4? and 44 and the windings of relay Llo io ground and lgrounded battery. llelay lt5 is mierated over the above described circuit and closes at its inner make contact` a circuit for operating slow releasing relay i7. .'\t the left hand make contact of relay l?, ground is connected to conductor 4,5, to which line switch brush 7 is connected, and this ground is effective to make this special third selector busy and also to hold the cut-olf relay 3 of line switch L1.

rille calling subscriber now operates the dial in accordance with the tens digit, which in this case is assumed to be :lL-t1. This will cause relay 4-6 to retract and attract its armature once. lith the armature of relay 4G retracted, a circuit is closed from ground, back contact of relay 4G, right hand make contact of relay 4?, winding of' chi/inge-over relay 4S, winding of primary stepping magnet 49 and first position of side switch wiper 5() to grounded battery. The primary stepping magnet 49 is operated one. point over this circuit and the change-over relay 48 is operated, thereby closing a circuit for energizingescape magnet 51. At the close of the tens4 series of in'ipulses, relay 46 main'- iains its armature energized sufficiently longl enough for relay 41S to retract its armature, illusv releasing the escape magnet and allowing the side switch wiper to go into its second position.

The subscriber now dials the units digit. which is again effective to operate relay 4G above described, except that in this incc the secondary stepping magnet 52 is oilerated, since side switch wiper 50 is in its second position. At the completion of this digi, relay '-18 and magnet 51 deenergizc. tlius advancing the side switch wiper into its third position. There is no busy test i'eature associated with the circuit of the special third selectors since it is desired that a plurality of calling subscribers may be connected to each central office radio receiver circuit simultaneously. A circuit is now closed for operating relay 53, traceable from ill!) lli lllti grounded battery, side switch wiper 50 in its third position and winding of relay 53 to ground. lelay 53, at its inner right hand make contact closes a circuit from ground, tirst position of control switch viper 54, back contact and winding of control switch magnet to grounded battery. Connection also extended from this same ground by way of third selector wiper 5G, to light lamp 57 associated with #2811. This lamp is an indication for the special radio operator to tune a radio receiver, such as 49, to station KUKA and then to connect this receiver by way of plug l1 and jack Jl to the calling line, which will presently be connected to this jack.

A circuit is now closed at the outer lett hand make contact ot' relay 53 by way ot conductors 5b and 59 and lower make contact of relay 4G for operating line relay G0 ot line switch L4, this line switch being as sociated with special third selector Rl. This circuit may bc traced from grounded battery, winding otl relay (it), inner, lower back contact of relay (il, conductor GQ, lower make contact ot' relay 4G, conductor 58, outer left hand contact ot' relay 53, conductor 59, outer, upper back contact ot relay G1 to ground. Relay GO is operated in` this circuit and functions to cause line switch L4 to connect with an idle first selector. This line switch will be advanced over busy tirst selector trunks by means ot' connections to ground, which will be found on contacts similar to 162. This ground is extended over wiper 63, inner back contact of relay G1, upper make contact ot relay (St), back contact and winding of stepping magnet (it to grounded batterv.

Let'it be assumed that the i'irst idle trunk tested, is one having conductors similar to 8, 9, 19 and 11. Since there is no ground on conductor S, motor magnet Gel will not be advanced beyond this set ot conductors and a circuit will be closed tor operating relay Gl, traceable from grounded battery, winding and bink contact ot magnet (34, winding o'tirelay G1 and lower make Contact oit relay 60 to ground. lelay 31 is operated and eX- tends the previously described closed circuit across condiu tors 59 and (l2, by way ot wipers and (3G to conductors 9 and 19 ot the selected tirst selector.

The subscriber is instructed to dial his own number and the tirst two digits ot this number are effective to cause the tirst and second selectors to be advanced to a trunk, which laids to a connector similar to C, as has been previously described in connection with a regular automatic telephone connection. It will be understood that the impulses generated by the calling subscribens dial are etiective to operate relay 2 which, by means ot its make contact, interrupts the circuit intluding the right hand windings of repeating coil 1 and the windings of relay 46 in series. These impulses are effective to vibrate the armature of relay 46 and by means o't' the lower make contact of this relay a circuit closed and opened including conductors a9 and (32, Jr'or operating the first and second selectors as above described. It will be noted that line switch L4 is provided with au additional wiper 67 and that this wiper connects with a tourt-h wire 11 ot the trunk circuit leading to a connector similar to C1. The calling subscriber will now operate the dial in accordance with the tens and units digits of his own number, this being etl'cctive to open and close the circuit across conductors 59 and (32, as above described for advancing the connector switch C1 in its primary and secondary movements, the detailed operation ot which has been described in connection with a regular automatic telephone connection.

vWith the connector' side switch wiper 1S in its third position a circuit is closed trom grounded battery, side switch wiper 18 in its third position, winding of relay Q3, conl i o i i oucmr 1l, line switch wiper (37, lower, outer make contar t of relay (il, conductor 70, winding ot relay T1, outer 1' ght hand make contact et relay 53, third selector wiper 72 and the terminal with which it is connected, winding 75l of transformer 74 to ground. This ein uit is etlective to operate relay 23 and extend this connection from ground on conductor 11 by way of the lower make contact of relay 23, wiper 75, conductor 76 to the mid-point ot the lett hand windings of repeating coil 1. This circuit is for the purpose of connecting the received radio signals to the calling line as will presently be described, and also for the purpose ot causing the connector Cl to discriminate between a regular automatic telephone connection and a connection back to the calling subscribers line used t'or receiving a radio program. 1n a connection ot the former class it has been shown that trunk 11 is not used, thus relay 23 is not operated, but in the latter case trunk 11 is used t'or the purpose ot' operating relay 23.

The operation or" relay opens at its upper back Contact, the circuit ot connector test wiper 211 and relay 29, thus preventing the operation ot relay 29 when a connection is made from a calling line by way ot' this connector', back to the same line. The opening ot the circuit of wiper 2l disables thc busy testing feature. in order that this line may be used either for an originating or a terminating regular automatic connection at the same time that it is being used for receiving a radio program.

During the time that relay etti is being operated to reiford the tirst digit otl the calling subscribcr"s number, a circuit is closed from ground, inner back contact otl relay 46, right fl H (iii

hand make eonptaft of relay 47, winding ot relay 48, resistance coil 68 and innei lett hand make contact of relay 53 to grounded battery. This circuit is ett'ective to operate relay 48, which in turn closes a circuit from ground, make contact of relay 48, control switch wiper 54, in its second position, back contact and winding ot magnet 55, to grounded battery. The control switch is thereby advanced to its third position. At the close of the tirst series of impulses correspending to the tirst digit ot the calling line, relay 48 retracts its armature and closes a crcuit from ground, back contact ot relay 48, control switch Wiper 54 in its third position, back contact and winding ot' magnet 55, to grounded battery, which circuit is ettective to advance the control switch to its t'ourth position.

During the time that relay 46 is be`ng operated to record the second digit of the calling line. relay 48, is operated and closes a circuit from ground, make contact ot' relay 48, control switch wiper 54 in its fourth position, back contact and winding ot magnet 55, to grounded battery, this circuit be ng ett'ective to advance the control switch to position 5. At the close ot the series ot impulses corresponding to the second digit ot the calling line, relay 48 retracts its armature and closes a circuit from ground, back contact ot relay 48, control switch wiper 54 in its titth pos tion, back contact and winding ot' inagnct 55 to grounded battery, this circuit being effective to advance the control switch into its sixth position.

During the time that relay 4G is heilig operatedV to record the third series ot impulses, relay 48 is energized and closes a circuit from ground, make contact ot relay 48, control switch wiper in its sixth position, back contact and winding of magnet to grounded battery, this circuit being effective to advance the control switch into position 7. At the close ot this series ot impulses, relay 48 rctracts its armature and closes a circuit from ground, back contact of this relay, control switch wiper in its seventh position, back contact and winding ot magnet 55 to grounded battery. this circuit being etfective to advance the control switch into its eighth position.

During the time that relay 4G is being operated to record the fourth series ot' impulses, relay 48 is energized and closes a circuit from ground, make contact otl relay 48, control switch wiper 54 in its eighth position,I back contact and winding ot magnet 55 to grounded battery, this circuit being etiective to advance the control switch into its ninth position. At the close ot this series of impulses, relay 48 retracts its armature and closes a circuit from ground, back contact of this relay, control switch Wiper 54 in its ninth position, back contact and winding of magnet to grounded battery, this circuity being effective to advance the control switch into position lO.

A circuit is now closed trom ground, control switch wiper 7G in its tenth position and Winding ot' relay 77 to grounded battery. Relay 77 is operated and at its left hand make contact places a short-circuit across conductors 62 and 59 tor the purpose ot holding the established connection to the calling line when the calling subscriber hangs up the receiver. Relay 77 opens, at its right hand back contacts, the releasing circuit for third selector release magnet 78 and control switch stepping magnet in order that these two switches will not be reieased when relay 47 deenergizes, atter the calling subscriber hangs up the receiver.

The calling subscriber now being connected Vith his own line replaces his receiver upon its switchhook, thus opening the circuit of relay 2, which deenergizes and at its make contact, opens the circuit ot relay 46, which rctracts its armature and in turn opens the circuit ot relay 47. which also deencrgizes. During the interval between they release oit relay 4G and the release ot relay.'v 47, a circuit is closed from ground, back contact of relay 46, right hand make Contact ot relay 47. winding ot' relay 48, resistance (58 and inner lett hand make contact ot' relay 58 to grounded battery. This cir cuit is ettective to energize relay 48, which in turn closes a circuit from ground, make contact ot relay 48, control switch wiper 54 in its tenth position, back contact and winding ot' magnet to grounded battery, this circuit being cttective to advance the control switch into its eleventh position. Shortly atter this, relay 47 deenergizes and opens the above traced circuit ot relay 48, thisy latter relay deenergizes and closes a circuit trom ground, back contact ot relav 48. con4 trol switch wiper 54, in its eleventh position, back contact and winding ot magnet 55 to grounded battery. this circuit being' citeetive to advance the control switch into its twelfth and last position.

lVhen the calling subscriber replaces the receiver upon its switchhook and rcieasesr relays 4G and 47, as above described. relax' 47, at itsl left hand make contact, removes ground from conductor 45, which is eii'ective to release the first selector. second selector and line switch used in estabiiehing connection with special third selector l. llvhen the control switch ad 'onces to its twelfth position, above described, wiper 80 connects ground to conductor 45, so that this special third selector cannot be selected by another calling party until it has been released .trom the present connection.

Rectangle 40, shown in the right central portion of Fig. 3, represents ay radio receiver of any approved type having` proper facilities for selecting different broadcast stations. This radio receiver is designed to rcceive stations within the present broadcast range. for example, those operating on wave lengths of approximately 20() to (39() meters. 'ires 4l and 42 may either connect to a loop antenna or to cieated antenna and ground connections. A radio receiver cir cuit r`ach as is shown iu Fig. 1 of the patent to J'. Scott Taggart No. 1,524,581. may be the circuit represented by rectangle 4t). The two wires leading to receiver 'l of this patent, instead of connecting to said receiver, may connect to wires and 83 shown leading out of' rectangle 49 of Fig. 3. 'lhere are a plurality of radio receivers, such as Al, A: and A as in-:licated in Fig. 1, located at an attendants positifim and it is the duty of this attendant to tune linch receivers to those stations which calling` sulsi'ribfrs desire to hear.

The circuits4 represented iiy rectangle 4() provide means whereby modulated radio frequency waves are received in an antenna circuit. connected to wires 4l and 42 of the radio receiver. These modulated carrier "aves are amplified and dctecteifl by the circuits of the radio receiver 4t). after which the detected or audio frequency signais are impressed on the winding of an audio transformer. lt will be understood that wires S2 and 83 may be permanently connected to the output of the detector or to the output of an audio amplifier stage of radio receiver 40, or these two wires may terminate in a pluoj. thus furnishing means by which the transftn'nier winding 84 may be selectably connected, either with the output of the detector or an audio stage of the radio receiver.

The audio frequency signals are induced in the secondary winding S5 of the audio transformer, after which they are applied to a modulator circuit rein-esented by the rectangle lil. An oscillator is also connected to thi` modulator and thee-e two devices in conibinathm serve the purpose of trifinslating into an intermediate frequency, the audio frequency signals produced by the broadcast station to which receiver 40 is tuned. t is proposed to operate oscillator U at a comparatively high frequency, that is, one that is above the audible range, but one that is not suiiiciently high to be within the range of the carrier frequencies used by broadcast stations. A suitable frequency for oscillator O may be fifty kilo-cycles. The eiilect of modulator M and oscillator O on the audio frequency signals is to apply a modulated fifty kilo-cycles or intermediate frequency waveto amplifier AM. This amplifier consists of circuits for amplifying most eiiiciently a modulated fifty kilo-cycle wave and will increase the amplitude of this wave and apply it to the tip and ring conductors of plug P1.

In order to simplify the drawings and the description of this invention, those circuits which are not closely related to the features of the invention are shown in diagrammatic form only. Oscillator O, modulator M and amplifier AM, may be well known circuits of' these devices, such as are indicated by O, M and A in Fig. 1 of the patent to J. Mills No. 1,457,447.

The modulated intermediate waves applied to the tip and ring conductors of plug P1 are now extended over the circuit including the tip and ring contacts of jack J1 and through winding 79 of transformer 74. T he secondary windingl 73 of this transformer is tuned to the intermediate carrier frequency, which appears in the out put of amplifier AM, this timing being accomplished by means of variable condenser 9o. Since this carrier frequency is not variable, but at all times consists of approximately a contant frequency irrespective of the wave length of the station being received, condenser 8G, when once set at the proper point for tuning the secondary circuit 73 of the transformer to this frequency, need not be changed, except to slightly increase or decrease its capacity to compensate for varying line conditions to which this circuit is connected.

The signal, which is induced into winding 73 of transformer 74, may now he traced from ground, winding 73, conductor 87, selector wiper 72, outer right hand make contact of relay 53, condenser 88, conductor 70, lower outer make contact of relay G1, wiper (57, conductor 11, lower make contact of relay 23, wiper 75, conductor 7 6, mid-peint of the left hand windings of repeating coil 1, at which point it divides and goes through condensers 89 and 90, both of the left hand windings of repeating coil 1 and both sides of the calling line conductors 91 and 92 in multiple, through windings 93 and 94 and condensers 95 and 9G associated with an impedance coil and winding 97 of transformer 98 to ground. The impedance coil windings 93 and 94 and condensers 95 and 96 are so proportioned that they will most e ficiently transmit current waves of' the intermediate frequency. Transformer 98 is also designed to efficiently repeat this intermediate frequency signal, after which it is detected by detector 99 and amplified by audio frequency amplifier 100 in a manner which is well known in the art.

The audio frequency signal in the output of amplifier 10i) is now impressed on the circuit including the loud speaker or rcceiver 101. The dotted lines connecting the radio receiver of' Fig. 2 to telephone line conductors 91 and 92 indicate that this radio receiver may he permanently connected to loo Cai

these line conductors or it may be connected by means of a key or by means of a plug and a jack.

From the above description it will be seen that a modulated high frequency radio signal is received by a receiver. such as 40. in the central office, after which the audio frequency component of this incoming signal is translated into a modulated intermediate frequency signal, amplified and then iinpressed on the telephone subscribers line by means of a simplex circuit. It will be noted that the expensive and complicated receiving apparatus is located at the central telephone oflice, where it may be more efficiently maintained and adjusted and that a very simple and inexpensive type of radio receiver is located at the subscribers substation.

Since the radio program is being received over a simplex circuit including the calling line wires in multiple and a connection to ground and since the calling line switch, such as L1 has been released, it will be evident that the calling subscriber, whose substation is represented by T1, may remove the receiver and establish an automatic telephone connection at this time, in the same manner as has been already described. It will also be evident that, while a radio program is being received over this line, the line may be selected by a connector, such as G1 and a terminating automatic telephone connection established.

The attendant operator in the telephone exchange may monitor the connection when plug P1 is in connection with jack J1, by operating the listening key 102. which operation connects a simplified radio receiver, indicated at A4, in multiple with the existing connection. Receiver A4 is not shown in detail, since it consists of a duplicate of the circuit of' the substation radio receiver as shown in the lower left hand corner of Fig, Q. The operator may make minor tuning adjustments by varying the setting of condenser 86.

If the calling subscriber fails to release the connection after the program has been discontinued, the attendant may operate key 103, which is effective to connect main battery by way of the sleeve contacts of the plug and jack to conductor 8T. which functions to short-circuit and release relay 'i' l, since this relay now has main battery on both of its terminals. The main battery on the left hand terminal of relay Tl applied from the th" d position of connector side switch wiper 18. The operation of key 103, likewise releases relay 23.

The release of relay 71 closes a circuit from ground, back contact of this relay, control switch wiper 54, in its twelfth position, back contact and winding of control switch stepping magnet 55 to grounded battery, this circuit being effective to restore the control switch to its first and normal position. Control switch wiper 80 disconnects the ground from trunk 45, thus releasing the line switch. first selector and second selector, which was connected to special third selector lll. Control switch brush 76 opens thc circuit of relay 77, which deenergizes and removes the short-circuit from conductors 62 and 59. thus releasing the connection which was established back to the terminals of the calling line, this connection including line switch Lt, first selector, second selector and connector.

Relay 77 at its inner back contact closes a circuit from ground, back contact of relay 47, off-normal contact 106 and winding of special third selector release magnet 78 to grounded battery, this circuit being effective to release third selector R1. At its outer right hand back contact, relay 77 closes a circuit from ground. back contact ot relay 47. control switch wiper 107 in any of its off-normal positions, back contact and winding of magnet 55 to grounded battery. This circuit4 and the one previously dcscribed including magnet 78 are for the purpose of restoring the third selector and its associated control switch in case the calling subscriber prematurely disconnects.

The operator now withdraws the plug P1 from jack J1 after which she may tune radio receiver 470 to some other staton and connect it by means of plug P1 to some other jack, similar to jack J1, which has its associated lamp similar to 57 lighted as an indication that it is desired to receive a program from said other station.

It will now be assumed that the calling subscriber desires to disconnect from station KUKA and listen to some other station. In this case he will remove the receiver of substation Tl from its switch-hook, which will function to cause line switch L1 to select an idle first selector as previously described. He will now dial a special release number consisting of four digits, and this act will be effective to cause the first selector. second selector and connector switches to be advanced to this special number in a manner previously described. In this particular instance` however. bank contacts similar to 31, 32 and 110 associated with this special release number are not Wired. Bank contact 10S). which is similar to contact 25 and is the one to which connector wiper Q4 makes connection, is connected to conductor T6 as shown in the upper central portion of Fig. 3, When the special release number has been dialled, ground from the third position of connector side switch wiper Q2, is applied to terminal 109 by way of connector brush 24 and this ground is eft'ectivc to short-circuit and release relay Tl of the control switch, this ground being applied to the left hand terminal of relay 7l, over conductors 7G, ll and 70. The ground on the right hand terminal of relay 7l is that applied through winding 73, of transformer Tft. Relay 'Tl will retract its armature and release the connection in a mauner previously described. The subscriber may now release this connection to the special number, after which he may dial a number corresponding to some other broadcast station.

Although the principle of this invention has been shown applied to a system in which the modulated high frequency waves are translated into intermediate frequency signals by means of certain modulator and oscillator circuits, it should be understood that this invention in its broad conception is not limited to the particular type of radio receiving circuits, modulator circuits, oscillating circuits and amplifier circuits, described in connection with this invention, since these particular circuits and the values assumed in the description, Amay be varied or modified in such a Way that they would still be within the scope olf the invention. For example, the circuit indicated by rectangle Al() may consist of a so-called shortwave receiver connected as shown in Fig. 5. ln this case the transformer, modulator, selector and amplifier may be dispensed with and the audio frequency signal in the output or receiver l() applied directly to 'the primary winding of transformer Tl, a'l'ter which it is connected to the calling telephone line over a simplex circuit in the manner previously described and received by the radio receiver circuit shown in Fig. el. It is to be understood that the circuit of Fig. l is connected to conductors 91 and 92 in place of the receiver circuit shown in Fig. 2. In this case the detector oil Fig. 2 is eliminated, since it is only necessary to receive the audio frequency signal and amplify it by amplifier 100 as shown in Fig. 1l.

Fig. G may likewise be substituted for A, radio receiver di), modulator lvl, oscillator and amplitier AM of Fig. Il. When the circuit ot' Fig. 6 is substituted as above mentioned, programs of music, news, information, etc., may be received in the form of audio frequency signals from a distant station, over wire lines connected to conductors 4l and 42 of Fig. 6, in which case they would be connected directly to transformer 7l by means o'l the plug and jack circuits, shown in Fig. 6. In this instance the radio receiving circuit located at the substation would be as shown in 6. lt would be connected to line Wires 91 and 92 in the same manner as previously described in connection with the radio receiver circuit shown in the lower left hand corner of Fig. 2, which in this instance would be eliminated.

It will be obvious that the general principle herein disclosed may be embodied 1n many other organizations dilfering widely from those illustrated Without departing from the spirit ol the invention as detined in the following claims.

lYhat is claimed is:

l. ln an automatic telephone system, a calling line, a called station, a discriminating trunk associated with said called station, means controlled over said calling line in series for thereafter extending said discriminating trunk to said calling line, and means including said discriminating trunk for disabling the usual busy test feature of said called line whereby a connection is eX- tcnded to said calling line over a simplex circuit including said calling line in multiple.

In an automatic telephone system, a calling line, a busy test circuit associated with said line, a called line, a radio receiving station, a discriminating trunk associated With said station, means controlled over the two sides ot said calling line in series for establishing a radio signalling connection from said station to said calling line by Way ot' said discriminating trunk, means controlled by said discriminating trunk for disabling said busy test circuit, and means for establishing a contemporaneous connection from said calling line to said called line.

3. The method of providing telephone service between subscribers stations and furnishing radio programs to certain of said stations which consists in successively establishing links in a telephone connection from a calling subscriber to a called subscriber under the selective control of a calling subscriber, and in furnishing a radio program to said calling subscriber by first directively setting up a control agency from the calling subscriber to the source of radio signals, and employing said control agency to directively establish a channel under the control of the calling subscriber from the source of radio signals to said calling subscriber.

l. In a combined telephone and program service system, a plurality of subscribers stations, a program transmitting station, means including a plurality of automatic switches and link circuits directively controlled from a calling subscribers station to establish a telephone connection from said station to any other subscribers station, means including certain of said lirst automatic switches and link circuits for establishing a connection directively controlled from the calling subscribers station to said program transmitting station,y and means controlled over Said last-mentioned connection Afor establishing a program transmitting channel Jfrom said program transmitting station to said Calling subscribofs station.

5. In a combined telephone and program Service system, a plurality of subscribt-ra station'f., a program transmitting station, means including a plurality of automatic switches and link circuits directively controllcd from a calling Subscriber@ Station to establish a telephone connection from said station to any other subscribers station, moans including certain ot said first automatic Switchcs and link circuits for establishing a connection dircctivcly controlled from thc callingr subscribers station to said program tramanittinr stationr` and means Controllcd ovcr said ast-mentioned connection tin' establishing a program transmitting channel from said program transmitting station to said c: lling` suhscribcrs station, said channel including thcrcin a simplex circuit.

In witness whcrcof, 1 hereunto subscribe my name this 13th day of November A. D. 1925.

VINFRED T. POWELL. 

